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PETERHEAD CCS PROJECT FRONT MATTER
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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i
Peterhead CCS Project Doc Title: Seismic Interpretation Report
Doc No.: PCCS-05-PT-ZG-0580-00002
Date of issue: 22/05/2015
Revision: K03
DECC Ref: 11.106
Knowledge Cat: KKD - Subsurface
KEYWORDS
Goldeneye, CO2, Captain Sandstone, Overburden, Aquifer, Seismic, Interpretation, Processing,
Depth Conversion.
Produced by Shell U.K. Limited
ECCN: EAR 99 Deminimus
© Shell U.K. Limited 2015.
Any recipient of this document is hereby licensed under Shell U.K. Limited’s copyright to use,
modify, reproduce, publish, adapt and enhance this document.
IMPORTANT NOTICE
Information provided further to UK CCS Commercialisation Programme (the Competition)
The information set out herein (the Information) has been prepared by Shell U.K. Limited and its
sub-contractors (the Consortium) solely for the Department for Energy and Climate Change in
connection with the Competition. The Information does not amount to advice on CCS technology or
any CCS engineering, commercial, financial, regulatory, legal or other solutions on which any reliance
should be placed. Accordingly, no member of the Consortium makes (and the UK Government does
not make) any representation, warranty or undertaking, express or implied as to the accuracy,
adequacy or completeness of any of the Information and no reliance may be placed on the
Information. In so far as permitted by law, no member of the Consortium or any company in the
same group as any member of the Consortium or their respective officers, employees or agents
accepts (and the UK Government does not accept) any responsibility or liability of any kind, whether
for negligence or any other reason, for any damage or loss arising from any use of or any reliance
placed on the Information or any subsequent communication of the Information. Each person to
whom the Information is made available must make their own independent assessment of the
Information after making such investigation and taking professional technical, engineering,
commercial, regulatory, financial, legal or other advice, as they deem necessary.
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PETERHEAD CCS PROJECT FRONT MATTER
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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Table of Contents
List of Tables iii
List of Figures iii
Executive Summary 1
1. Introduction 3
2. Geological Setting and Data Availability 3
2.1. Regional Geology 3
2.1.1. Geological Setting 3
2.1.2. Structural History 4
2.1.3. Regional Stratigraphy 5
2.2. Charge History 1
3. Seismic Data Availability 2
4. Seismic Processing 1
4.1. 1994 3D Greater Ettrick Regional Survey 2
4.2. 1997 3D East Ettrick Survey 2
4.3. 2001 3D Pre-Stack Depth Migration (PreSDM) 4
4.4. 2010 HiDef processing 6
5. Seismic-to-Well Ties 6
6. Horizon Interpretation 9
6.1. Top Nordland Group 11
6.2. Top Lark Formation (Top Westray Group) 11
6.3. Top Horda Formation (Top Stronsay Group) 11
6.4. Top Beauly Member (Top Moray Group/Dornoch Formation) 11
6.5. Top Coals 11
6.6. Top Dornoch Mudstone Unit 12
6.7. Top Lower Balmoral Sandstone and Tuffite Unit 12
6.8. Top Chalk Group/Top Ekofisk Formation 12
6.9. Top Tor Formation 13
6.10. Top Hod Formation 13
6.11. Top Plenus Marl Formation 13
6.12. Top Rødby/Base Hidra Formation 13
6.13. Top Captain Sandstone (Subunit E, Top Reservoir) 13
6.14. Intra Captain Subunit C 15
6.15. Intra Captain Subunit A 16
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6.16. Base Captain Sandstone (Base Reservoir) 17
6.17. Top Scapa Sandstone Subunit 18
6.18. Base Cretaceous Unconformity (BCU) 18
6.19. Top Triassic (Top Heron Group) 18
6.20. Top Zechstein Group 18
7. Fault Interpretation 19
7.1. Top Rødby/Top Captain Faults 19
7.2. Intra Reservoir Faulting 19
7.3. Base Captain Faults 19
7.4. Base Cretaceous Unconformity (BCU) Faults 20
7.5. Overburden Faulting 21
8. Depth Conversion 23
9. Overburden Features 26
9.1. Seafloor pockmarks 26
9.2. Subglacial channels 27
9.3. Palaeo-seafloor piercements 28
9.4. Eocene Coals and Palaeo-shoreline 29
9.5. Lensing effects 30
10. Regional Aquifer Seismic Interpretation 32
11. Regional Aquifer Depth Conversion 35
12. Conclusions 37
13. Glossary of Terms 38
14. Glossary of Unit Conversions 39
15. References 40
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List of Tables
Table 3-1: Acquisition Parameters 2
Table 6-1: Interpreted seismic horizons 9
Table 8-1: Velocities used for depth conversion (depth in feet). 24
Table 8-2: 7-Layer Depth Conversion residuals (ft) 26
Table 14-1: Unit Conversion Table 39
Table 14-2: Well name abbreviations 39
List of Figures
Figure 2-1: Distribution of Captain Sandstones across outer Moray Firth: Captain Fairway
highlighted in yellow; basinal areas in pale green 4
Figure 2-2: Generalised stratigraphy of the Goldeneye area 1
Figure 2-3 Hydrocarbon source areas for the Captain Fairway reservoirs 1
Figure 3-1: Regional seismic coverage in Halibut Trough 3
Figure 3-2: 3D seismic surveys available over the Goldeneye Field 1
Figure 3-3: Regional W-E Seismic Line along Halibut Trough. 1
Figure 4-1: Gridded coal bodies in the final velocity model (coordinates in m; velocity in m/s) 5
Figure 4-2: Comparison of PosSTM (1999) and PreSDM (2001) volumes 5
Figure 4-3: Comparison of 2001 PreSDM and 2010 HiDef data 6
Figure 5-1: Seismic-to-well tie through reservoir section (14/29a-3), depths in ft [1ft =
0.3048m]. 7
Figure 5-2: Seismic-to-well tie for well 14/29a-2 8
Figure 6-1: Seismic section (S-N) in depth through wells 20/4b-6 and 14/29a-2 showing
interpreted horizons. 10
Figure 6-2: Paleo-shoreline and drainage network as observed in the semblance map (from the
Greater Ettrick 3D survey) through the Eocene coals. Semblance extracted from
interpreted coal event at approximately 760-975 m TVDSS. 12
Figure 6-3: North-south seismic section in depth (ft) through wells 20/4b-6 and 14/29a-2. 14
Figure 6-4: Top Captain Sandstone (base case) in depth. 15
Figure 6-5: Cross sections though the Goldeneye Field showing high and low case
interpretations. Well paths projected onto lines of section. Fluid contacts
extended for clarity. 17
Figure 7-1: Top Captain fault polygons 20
Figure 7-2: BCU fault polygons overlain on BCU semblance horizon 21
Figure 7-3: North-south TWT reflectivity seismic section, equivalent semblance section and
Top Captain map for location. 22
Figure 8-1: Supra-Beauly wedge in section. 25
Figure 8-2: Map view of Supra-Beauly wedge: isochore thicknesses (ft). 25
Figure 9-1: Pockmarks interpreted from site survey data compared to indications of seabed
depressions from interpretation of 2002 PreSDM seismic survey. 27
Figure 9-2: Subglacial channel (Field outline in red). 27
Figure 9-3: Imprint of Pleistocene channel on Top Horda dip map 28
Figure 9-4: HiDef seismic at Beauly level through palaeo-pockmarks (purple boxes). 29
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Figure 9-5: Edge of coal layers create vertical seismic disturbance directly below. 30
Figure 9-6: Focusing anomaly on HiDef survey 31
Figure 9-7: Vertical seismic artefacts below tunnel valleys, Danish North Sea 31
Figure 10-1: Top Captain TWT seismic interpretation seed grid. 32
Figure 10-2: Regional west-east seismic section in TWT from the Cromarty Field to the
Hannay Field with the Top Captain interpretation (light blue) and the Base Captain
interpretation (green). 33
Figure 10-3: Captain Sandstone aquifer model, isochore (ft). 34
Figure 11-1: Regional Top Chalk depth surface. (Vertical exaggeration x 5). 35
Figure 11-2: Average velocity map (seabed to Top Captain). 36
Figure 11-3: Regional Top Captain depth surface (ft). 37
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PETERHEAD CCS PROJECT Executive Summary
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
The information contained on this page is subject to the disclosure on the front page of this document.
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Executive Summary
This report documents the geophysical work carried out to characterise the Goldeneye CCS (Carbon Capture and Storage) storage complex in support of assessing the storage capacity of the reservoir and the identification of any potential leak paths to the surface. The work is based on the most recent seismic survey covering the Goldeneye field area, the East Ettrick Survey, which was acquired in 1997 and reprocessed in 2001 as Pre Stack Depth Migration (PreSDM) to improve the imaging of the subsurface. The report explains the rationale for the identification and interpretation of key seismic events (horizons) and discontinuities (faults) from the sea floor to, at depth, Upper Jurassic rocks. Twenty horizons were interpreted across the PreSDM seismic volume including the top reservoir, termed the Top Captain Sandstone. As the interpretation was carried out in the time domain, conversion to depth was then performed using a 7-layer velocity model. The result showed the reservoir to be a domal structure whose internal layers pinch out northwards against a structural high. The overlying seal, composed of the Upper Valhall and Rødby Shales and the Lower Chalk, follows the same domal structure and is mapped as continuous across and beyond the reservoir extent. Successively shallower intervals include both secondary seals (the Lista and Dornoch Mudstones) and secondary storage horizons (the Upper Chalk, Mey/Balmoral and Dornoch Sandstones): they are gently tilted, shallowing to the north and the west. Faults have been interpreted with three main focuses. Below the Captain reservoir, predominantly E-W faults at the Base Cretaceous Unconformity helped define the field geometry. At the level of the reservoir and its immediate seal faults were assessed for reservoir compartmentalisation and seal continuity: they are again E-W, discontinuous, and with offsets significantly less than the reservoir or the seal thickness. Above the reservoir and seal, faults were assessed for possible linkages to the surface. NW-SE faults are seen in the Chalk and rarely in the Mey sandstones. These faults are not connected to those at reservoir level and do not extend to the shallower layers. Particular attention was paid to acoustically-significant features in the overburden above the Goldeneye reservoir. These features complicate interpretation at depth: seafloor pockmarks, subglacial channels, palaeo-seafloor piercements and coals. These cause local artefacts in the seismic data such as striping and apparent faulting, and were carefully assessed by proprietary high-definition reprocessing (“HiDef”) of the seismic volume. This allowed improved separation of artefact from true signal and confirmed that there were no through-going fault or fluid escape structures in the area. The regional Captain Sandstone aquifer was also mapped for some 180 miles east-west across four adjacent seismic datasets including the Goldeneye PreSDM volume. Four geological horizons were interpreted: the top Rødby (seal), top and base Captain Sandstone and the base Cretaceous. The regional depth conversion was carried out using a single velocity layer to top Chalk and well-derived average velocity maps to top and base reservoir. The aquifer is characterised as a long E-W trending ribbon that shallows progressively eastwards. The seismic interpretation summarised above provides evidence that there are no features indicating leakage from the reservoir and no features that could be considered likely to impair the ability to store CO2 in Goldeneye. The seismic horizons and faults have been used as input data to create three static model suites covering the Goldeneye Field itself, the overburden above the Goldeneye Field, and the regional aquifer of the Captain Sandstone. These suites are described in the document KKD 11.108 “Peterhead CCS Project Static Model Reports”. They were used as the input to dynamic and
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PETERHEAD CCS PROJECT Executive Summary
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geomechanical models that were needed to further assess the storage and containment capacity of the complex, the repressurisation behaviour of the Captain Aquifer and possible interactions with other users of the Captain Sandstone.
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PETERHEAD CCS PROJECT Introduction
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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1. Introduction
This report forms part of the subsurface documentation in support of the Peterhead CCS Project. It
compiles the geophysical data, methods and interpretation results which were used to create the
framework for static and dynamic models of the Goldeneye field, the overburden and the regional
aquifer, and for geomechanical modelling. The geophysical data is largely based on wells and seismic
surveys which were acquired during the exploration and development phases of the Goldeneye field
and of the broader Captain Sandstone Fairway.
The report summarises the regional geological setting, followed by a review of the data available for
the work. The data processing is then addressed, followed by the successive steps involved in seismic
interpretation to arrive at a valid horizon-fault framework in depth. This includes description of each
horizon addressed. Special attention is paid to overburden features that produce artefacts on
underlying layers and the use of high-definition reprocessing to identify these. Finally, seismic
interpretation of the regional Captain Sandstone aquifer is addressed.
The geophysical work for the Peterhead Project is specifically aimed at providing a structural
framework – the geological horizons and faults – for the area. The data does not lend itself to the
recognition of fluid contacts, static or dynamic reservoir properties, or the differentiation of
depositional facies.
This report is an update of the previously-released geophysical evaluation report for the Longannet
CCS project to incorporate work not available at that time: the use of a proprietary high-definition
reprocessing step to assess overburden artefacts. The section on overburden artefacts has also been
expanded to describe these issues more fully. Finally, the opportunity has been taken to correct minor
inconsistencies where found.
2. Geological Setting and Data Availability
2.1. Regional Geology
The regional studies related to the Goldeneye accumulation encompass the Inner and Outer Moray
Firth regions of the UKCS (United Kingdom Continental Shelf) Central North Sea. The area is
dominated by the Halibut Horst, a feature that remained emergent throughout most of the Jurassic
and Lower Cretaceous periods. The Goldeneye Field is situated south of the horst on the northern
edge of the South Halibut Basin: the field is a gas condensate accumulation with a thin oil rim. The
main reservoir is formed by the Early Cretaceous-aged Captain Sandstone Unit, a turbidite sandstone
with good reservoir properties. Goldeneye was discovered in 1996 by Shell/Esso well 14/29a-3,
which encountered a gas column of 92 m. In the following years three appraisal wells were drilled:
1998 Amerada 20/4b-6 (South), 1999 Shell/Esso 14/29a-5 (South-East) and 2000 Amerada 20/4b-7
(South-West). In 2004 five development wells were drilled (see Figure 6-4).
2.1.1. Geological Setting
The shelf edge depositional setting of the Lower Cretaceous (latest Aptian–earliest Albian) resulted in
ribbon-like deposition of the Captain sands extending along the southern margins of the Halibut
Horst (Blocks 13/23, 13/24, 13/29 and 13/30) and the South Halibut Shelf (Blocks 14/26, 14/27,
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14/28, 14/29, 14/30, 15/26, 21/1). The deposition of the Captain sands continues along the
southern margins of the Renee Ridge through the Glenn discovery and towards the Britannia Field
area (Blocks 21/2, 21/3, 21/4 and 21/5) (Figure 2-1). The system is termed the “Captain Fairway”.
Figure 2-1: Distribution of Captain Sandstones across outer Moray Firth: Captain Fairway
highlighted in yellow; basinal areas in pale green
2.1.2. Structural History
The Goldeneye Field is located at the confluence of an E-W (East-West) fault system defined by the
Halibut Horst, and a SW-NE (Southwest – Northeast) system in the South Halibut Basin. The
Captain fairway west of Goldeneye is also influenced by SW-NE faults of the Smith Bank Horst and
Inner Moray Firth Basin and to the east by a NE-SE system related to the Witch Ground Graben
(Figure 2-1).
Formation of the Moray Firth rift system began in the Permian and continued through to the Jurassic
when the main features seen today became established. An unconformity at Base Jurassic heralded
the initiation of tectonism whilst Late Jurassic (Late Cimmerian) rifting resulted in the development
of a series of tilted fault blocks and associated half-grabens [1]. The imprint of older lineaments is
apparent: the north-easterly orientation of the Inner Moray Firth and South Halibut Basins is mainly
aligned to Caledonian basement faults whilst the east-west orientation of the Halibut Horst is
attributed to alignment with Hercynian extensional trends [2].
A regional unconformity at Base Cretaceous is followed by early Cretaceous subsidence with minor
compression, and Lower Cretaceous sediments passively infilled the pre-existing deep-water basin, on
lapping the Jurassic against the main structural highs. There was also a fundamental change in the
tectonic regime at Aptian-Albian level related to the Austrian tectonic event [3], which significantly is
the period when the Captain sands were deposited. During this time there was a diminution of the
HANNAY
West BankHigh
Smith BankHorst
Halibut Horst
NorthHalibutShelf
South HalibutShelf
EttrickSub-Basin
CromartySub-Basin
BanffSub-Basin
Grampian Spur
PeterheadSub-Basin
Peterhead
Ridge
Western
Graben
Buchan
Horst
N. HalibutBasin
FladenGround
Spur
Forties -Montrose
High
Renee Ridge
Buchan
Sub-Basin
ReneeSub-Basin
Scotland
Grampian Arch
022
018
021020019
012
013
015
016
014
GOLDENEYE
BLAKE
CROMARTY
CAPTAIN
ATLANTIC
HANNAY
BRITANNIA
1°0'0"E
1°0'0"E
0°0'0"
0°0'0"
1°0'0"W
1°0'0"W
2°0'0"W
2°0'0"W
58
°0'0
"N
58
°0'0
"N
360000
360000
380000
380000
400000
400000
420000
420000
440000
440000
460000
460000
480000
480000
500000
500000
520000
520000
540000
540000
560000
560000
580000
580000
6380
000
6380
000
6400
000
6400
000
64
200
00
64
200
00
64
400
00
64
400
00
64
600
00
64
600
00
648
000
0
648
000
0
GOLDENEYE FIELD
GOLDENEYE LOCATION, WITHREGIONAL STRUCTURAL ELEMENTS
Shell Exploration & ProductionShell U.K. Limited
ED_1950_TM_0_N
Projection: Transverse_Mercator
False_Easting: 500000.000000
False_Northing: 0.000000
Central_Meridian: 0.000000
Scale_Factor: 0.999600
Latitude_Of_Origin: 0.000000
Linear Unit: Meter Drawn by: EPT-IT-ED - Geomatics EP200910306998001
0 5 10 15 20
Kilometres
Original page size A4
Author: Cliff Lovelock
Date issued: October 2009
Scotland
Project: UKCS Demonstration Competition
Date updated: October 2012
Legend
Oil field
Gas field
Wet gas, gas condensate field
Oil and gas field
Oil field, post production
Gas field, post production
Oil field with gas cap, post production
GLENN
Outer Moray Firth
Basin
South Halibut Basin
Inner Moray Firth
Basin
Captain Trough
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influence of basin subsidence and the start of greater control on the basin form by a mild N-S
compressive regime reactivating the Halibut Horst and other local structural highs. Post-rift basin
infill continued with the Chalk which draped the residual Lower Cretaceous topography and
onlapped across the Halibut Horst.
A major change in structural regime and sedimentation occurred in the Early Tertiary due to ca.1km
of uplift of the Inner Moray Firth, Scottish Highlands and the East Shetland Platform areas resulting
in a regional eastward tilting of the area, uplifting the Chalk and Lower Cretaceous to allow partial
erosion and exposure at surface in the Inner Moray Firth. During this period large quantities of
clastics were deposited in the Outer Moray Firth and Central Graben areas. There was also a
continuation of the mild north-south compressive regime which warped the top chalk surface and
funnelled the sands west-east through the basin.
2.1.3. Regional Stratigraphy
The regional stratigraphic column for the Outer Moray Firth is shown in Figure 2-2. At the top it is a
Quaternary and Tertiary cover of interbedded sands, shales, claystones and lignites, broadly
thickening towards the east. In the Quaternary, Pleistocene glacial channels of dominantly NW-SE
orientation were cut across the sea floor and infilled with sediments of different acoustic properties
that create artefacts in underlying layers. The upper Tertiary Nordland and Westray Groups are mud-
dominated intervals whilst the lower Tertiary Moray and Montrose Groups are sandier with a large
variability in sand/shale ratios. Sand appears more abundant towards the east. Coals are present in
the Moray Group, which cause velocity anomalies and initiate artefacts into the underlying reflectors.
Rapid sedimentation in the Lower Tertiary resulted in elevated pore pressures and diapir-like palaeo-
seafloor piercement features that terminate within the Tertiary section.
Below the Tertiary clastics is a chalk section of fairly uniform thickness: the Upper Cretaceous Chalk
is the oldest formation to be deposited over the entire Halibut Horst. Prior to this the Halibut Horst
area is believed to have been emergent. The Chalk itself has an irregular top surface due to later uplift
and erosion.
Emergence and erosion of the Halibut Horst, and storage of resultant clastic sediments on both the
north and south Halibut shelfal areas, is believed to have contributed significantly to turbidite
deposition through the Lower Cretaceous and Jurassic in the Outer Moray Firth. This sand
deposition took place in a punctuated way against a background deposition of hemipelagic shales,
marls and occasional limestones in basins and sub-basins of variable thickness.
The Lower Cretaceous Captain Sandstones of Albian–Aptian age are generally more sand rich and
massive than the underlying Ryazanian-Barremian sands. The latter appear (from log signatures and
seismic expression) to be of more classical low density fan-type turbidites as opposed to the massive,
blocky, sandy debrite/high density turbidites of the Captain Sandstones. A regional unconformity
defines the base of Cretaceous sedimentation.
Good reservoir quality turbidite sands are also found within the Upper Jurassic Kimmeridge Clay
Formation. Underlying the Kimmeridge Formation, Upper/Middle Jurassic paralic sediments were
deposited (e.g. Heather/Pentland Formations) above the Base Jurassic unconformity.
Below the Jurassic section lie Triassic silts and shales of the Smith Bank Formation, the Permian
Zechstein and Rotliegend Formations and the deeper sand rich clastics of Carboniferous and
Devonian age. Below the Devonian sediments, basement granites are thought to form the core of
the Halibut Horst.
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Figure 2-2: Generalised stratigraphy of the Goldeneye area
Goldeneye Project Team
September 2010
Goldeneye Area Jurassic/Cretaceous lithostratigraphy: reservoir is Captain Sst MbrGoldeneye Area Jurassic/Cretaceous lithostratigraphy: reservoir is Captain Sst MbrGoldeneye Area Jurassic/Cretaceous lithostratigraphy: reservoir is Captain Sst Mbr
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2.2. Charge History
Geochemical analysis of oil and gas samples from fields and accumulations along the Captain fairway
lead to the interpretation of a multi-staged charge history for the Goldeneye structure (Figure 2-3).
Stage Ia: A palaeo oil-water contact is recognised at 8385 ft (2555 m) TVDSS in well 14/29a-
3, indicating that the Goldeneye structure was initially filled with oil. This oil charge, from a
‘kitchen’ between the Goldeneye and Ettrick fields, may have occurred as early as 120-80 Ma
ago. The early charge preserved the original high permeability in the upper part of the
reservoir.
Stage Ib: Subsequent to this, oil charge continued from the deeper parts of the kitchens in
the Ettrick Sub-basin, gradually filling the remaining column down to around 8780 ft
(2676 m) TVDSS.
Stage IIa: After the Goldeneye structure was completely filled with oil, it was tilted, resulting
in a reduction of the vertical relief of the paleo-accumulation and allowing oil to spill. The
most likely timing of that event is at the beginning of the Tertiary, around 60-55 Ma, when
regional eastward tilting occurred and the basin deepened significantly.
Stage IIb: As a result of the regional E-W tilting of the South Halibut Basin, which includes
the Goldeneye structure, large amounts of gas were released from the deep Fisher Bank Basin
kitchen in the east. The released gas then could enter and migrate through the eastward
dipping Captain fairway. On its way through the Captain fairway, the gas flushed existing oil
accumulations leaving completely gas filled structures in Glenn, Hoylake, Goldeneye and
Cromarty. With flushing happening around 50-60 Ma, most of the flushed oil probably
leaked to the surface and was lost from the system. Some of it may also have migrated into
shallow traps, resulting in the shallow heavy oil accumulations which are known to exist in
this area.
Figure 2-3 Hydrocarbon source areas for the Captain Fairway reservoirs
Stage IIIa: Due to continuous and substantial burial during the Tertiary (thickness of
Tertiary >4500 ft [1370 m]), pressure increased and gas was compressed. In this way, space
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in the trap was created for some oil to accumulate below the gas condensate column. If gas
flushing from the Fisher Bank Basin had continued during this period, no additional trapping
volume would have been preserved and we would not find an oil rim today. Thus, gas
migration from the Fisher Bank Basin must have stopped almost completely soon after the
oil was flushed out of the Goldeneye structure. Faulting in the Glenn area may have caused
this.
Stage IIIb: Due to the presence of shale barriers below the GOC, oil is not homogeneously
distributed below the gas, but compartmentalised. In the north of the Goldeneye
accumulation (l4/29a-3) where Captain sands scour directly into the Kimmeridge Clay, the
local kitchen expels oil at very low maturity (<0.7%VR/E). In the south (20/4b-6), charge is
mainly coming from the deeper and more mature kitchens of the Buchan and Ettrick area. In
the east (14/29a-5) oil may have spilled directly from Hoylake. It is important to mention
that maturity differences are limited to the heavy fraction (C30 range). The light ends of
Goldeneye oil samples are relatively well mixed with the overlying gas phase, indicating that
the oil and gas is in direct contact across the accumulation.
Geochemical analysis and basin modelling results imply therefore that the aquifer to the Goldeneye
field is continuous in the east, all the way to a fault zone in the vicinity of the Glenn accumulation
(UKCS Block 21/2). It is harder to estimate the extent of the western aquifer from the available
geochemical data, but would appear to extend at least as far as the Atlantic field. From dynamic
simulation and history match, as well as informal discussions with other operators in the area, it
seems that there is continuous pressure communication from Goldeneye to beyond the Atlantic field
– as far as the Blake field, across the Grampian Arch in UKCS Block 13/24.
3. Seismic Data Availability
Several seismic datasets were available that cover the South Halibut Trough, including 2D regional
lines, the 1994 Greater Ettrick Regional 3D, the 1997 East Ettrick 3D, the 2001 Goldeneye PreSDM
3D and the 2001 Blake 3D (see Figure 3-1). The Goldeneye Field itself is covered by several vintages
of 3D seismic (Figure 3-2). Shell acquired the Greater Ettrick Regional 3D Survey, a low-fold (20)
quad-quad reconnaissance 3D survey in 1992, which was subsequently reprocessed in 1994. The
Goldeneye discovery well 14/29a-3 was drilled on this dataset. Data quality is moderate to poor at
target level. Following the discovery, a target oriented 230 km2 high-fold (96) seismic dataset the
East Ettrick 3D Survey was acquired in 1997 which was centred on the Goldeneye Field and covered
parts of Blocks 14/28b, 14/29a, 14/30a,b,c, 20/3b, 20/4b and 20/5c. This 3D survey was used for
the Field Development Planning for the Goldeneye Field.
Despite extensive efforts during the (re-)processing of the 1997 3D seismic data, seismic data quality
still remained only moderate around the target level due to the laterally variable shallow coal layers.
In order to address these data quality issues a full 3D Pre-Stack Depth Migration (PreSDM) was
carried out in 2001. This PreSDM dataset provided significant improvements in reflector continuity
and resolution, and in fault plane definition. The PreSDM seismic cube was used to identify the
development well locations prior to the start of development drilling in 2003.
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3
Figure 3-1: Regional seismic coverage in Halibut Trough
470.00
13/30A-4
337.85
14/28B-2
830.29
14/29A-3160.88
14/29A-4
624.42
14/29A-5
272.92
14/30B-3
329.96
20/4B-3218.31
20/4B-6
392.82
20/5C-6
250.00
14/28b-4
83.88
13/24-1
102.00
13/30-1
328.00
13/30-2
345.55
13/30-3
229.00
14/26-1
179.41
14/26A-6
14/26A-7A
229.00
14/26A-8
194.50
13/29B-6
412000 416000 420000 424000 428000 432000 436000 440000 444000 448000 452000 456000 460000 464000 468000 472000 476000 480000 484000 488000 492000 496000 500000 504000 508000 512000
412000 416000 420000 424000 428000 432000 436000 440000 444000 448000 452000 456000 460000 464000 468000 472000 476000 480000 484000 488000 492000 496000 500000 504000 508000 512000
6410000
6415000
6420000
6425000
6430000
6435000
6440000
6445000
6450000
6455000
6460000
6465000
6410000
6415000
6420000
6425000
6430000
6435000
6440000
6445000
6450000
6455000
6460000
6465000
0 2500 5000 7500 10000m
1:260000
SeismicLegend
UKCS BlocksHannay_9496Goldeneye_8592Atlantic_6450Cromarty_6248Blake_5260Captain Aquifer Extent
Regional Cretaceous FaultsAbandoned, oil productiveAbandoned, dryAbandoned, oil showsAbandoned, gas productiveSuspended, gas and condensate productiveAbandoned, oil and gas shows
Abandoned, gas and condensate productiveAbandoned, oil and condensate showsSuspended, oil productiveAbandoned, gas shows, condensate to surfaceAbandoned, gas shows Seismic Cov erage in Halibut Trough
Shell UK Ltd
Map Reference Number
Model Name/Horizon Name
Map Date
Owner(s)SP-AQ010D3-6.1
Captain Aquif er
September 2010
Goldeney e Project Team
Country
Projection
Datum
Coordinate System
Central Meridian
Geodetic Parameters
Unit of Measure
UK
TM 0 NE
ED 50
ED 1950 TM 0 N
0 deg
EPSG 1311
Metres
14/21 14/22 14/23 14/24 14/25
14/26 14/27 14/28 14/29 14/3013/3013/2913/28
13/2513/2413/23
20/1 20/2 20/3 20/4 20/519/3 19/4 19/5
21/1
15/26
15/21
2001 PSDM
Goldeneye Survey
Halibut Horst
1994 Greater Ettrick
Regional 3D Survey
Eastern Spec 3D
Survey
2001 Blake 3D
Survey
Halibut Trough AOI
Blake
Cromarty
AtlanticGoldeneye
Hannay
1994 Greater Ettrick Regional 3D
2001 Goldeneye PSDM
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PETERHEAD CCS PROJECT Seismic Data Availability
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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1
Figure 3-2: 3D seismic surveys available over the Goldeneye Field
Goldeneye Project Team
September 2010
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PETERHEAD CCS PROJECT Seismic Processing
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1
Seismic interpretation of the Captain Sandstone is generally difficult due to problems in imaging the
reservoir itself because of the poor impedance contrast at top reservoir between the Captain
Sandstones and the overlying Rødby shales. The seismic image quality at reservoir level is also
reduced due to the effect of the overlying lithology. The overburden includes glacial channels,
stacked, laterally varying, low-velocity coal layers and a thick high-velocity Chalk section. The glacial
channels and coal layers are responsible for buried statics (move-out distortion), and amplitude
effects due to focussing of energy and absorption losses. The Chalk layer causes marked ray bending
which is exacerbated by the high degree of rugosity exhibited by the Top Chalk. In addition, the
seismic data are contaminated with water-bottom multiples and strong long-period multiples
generated by the coal and chalk interfaces.
Figure 3-3 shows a regional seismic line running approximately west to east in the Outer Moray Firth
(post-stack time migrated data). This regional line shows that data quality deteriorates below a single
coal layer and that degradation is more severe below stacked coal layers. The number of coal layers
above the Goldeneye Field varies from one to four. The regional line also shows an increase in the
relief of the Top Chalk interface in the vicinity of the field. The Captain Sandstones dip about one to
two degrees from West to East.
Figure 3-3: Regional W-E Seismic Line along Halibut Trough.
Note: Display is in TWT (Two-Way Time). The Goldeneye Field is located to the right of the display at around 2100 ms
(2530 m).
The polarity convention for these seismic data is that a hard kick increase in acoustic impedance is
displayed as a negative number, shown as a red loop in all displays and figures in this report.
4. Seismic Processing
The seismic processing applied to the two main seismic surveys (three seismic volumes) used in this
study is detailed below. The Goldeneye Static Field Model and the Goldeneye Overburden Model
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2
were both constructed from interpretations based on the 2001 PreSDM seismic data, whilst the
Aquifer Static Model was constructed from interpretations that also use the Blake and Eastern Spec
surveys.
4.1. 1994 3D Greater Ettrick Regional Survey
A 20-fold 3D dataset was acquired in 1992 with a Quad/Quad set-up using 3 km streamers. The
dataset was reprocessed in 1994. Data quality, temporal resolution and Signal-to-Noise ratio is poor
at target level, and direct mapping of the top reservoir is difficult.
4.2. 1997 3D East Ettrick Survey
From July to September 1997 a target orientated 234km2 3D seismic survey was acquired by Western
Geophysical using one airgun source and six streamers. The survey was centred on the Goldeneye
Field and covered parts of Blocks 14/28a, 14/28b, 14/29a, 14/30a, 14/30b, 14/30c, 20/3b, 20/4b
and 20/5c. The Captain reservoir was not well-imaged by previous 2D and 3D seismic data, and so
the survey acquisition parameters were designed to maximise resolution of the target interval between
2.0–2.5s TWT. Key acquisition parameters are given in Table 4-1 below.
Table 4-1: Acquisition Parameters
Acquisition Parameter Data
Survey size (full-fold) 234 km2
Streamer length 3600 m
Record length 6 s
Fold 96
Bin size 6.25 m x 18.75 m
Near offset 125 m
Sample interval 2 ms
Sail-line direction E-W
Data processing was carried out in 1997 and 1998 by CGG, subsequently reprocessed by Veritas in
2000/2001 in preparation for PreSDM (Pre-stack depth migration, see next section). Processing
parameters are summarised below:
Reformat from SEGD to in house.
Apply zero phase conversion filter (designed according to Shell method 3).
Merge navigation and seismic.
Spherical Divergence to be T squared.
First break mute to be: Near offset 0.0 seconds, Far offset 3.1 seconds.
Swell noise attenuation, 5 Hz 18 dB/Octave low cut filter, F/K filter ±12 ms per trace
applied from 3.25 seconds (to be applied to all lines).
Q compensation of 136 with reference frequency 175 Hz.
K-filter with 0.33 Nyquist cut. AGC wrap.
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3
Tau-p de-convolution: Transform ± 750p's.
Design: near offset 500-4100, far offset 700-4600 ms.
Time
Mute: Rayparm Time, ms Velocity, ms
-750 2,000 1333
-500 3,000 2000
-200 6,000 5000
200 6,000 5000
500 3,000 2000
750 2,000 1333
Operator length 360ms + 60ms gap length.
XT DBS: Design: Near offset 500 – 4500 ms, far offset 3500 – 5900 ms
240 ms operator + 48 ms gap length.
SCAC design windows to be near 1800-3800, far 3200-4500.
SCAC 500 x 500 smoothing filter.
Sort to 2D cdp gathers .
NMO using smoothed 90% of velocity field (5 point spatial and temporal filter).
AGC.
Radon Demultiple: forward transform –800 to +1800 ms
notch removed 0 to +1800 ms
AGC removed.
NMO removed.
NMO using 100% of smoothed velocity field.
AGC.
Anti-alias K-filter.
AGC removed.
Drop alternate traces.
Re-apply first break mute.
Remove spherical divergence correction.
Additionally, Shell proprietary noise suppression software was applied (SOF-filtering) followed by
spectral whitening. However, seismic data quality still remained only moderate around the target
level. The reflectivity data was inverted to acoustic impedance to better understand the extent of the
Captain sands and the distribution of reservoir parameters. This was a Jason model-driven
constrained sparse-spike inversion. As the data quality did not allow simultaneous AVO inversion, a
mid-angle stack was inverted to elastic impedance. Additionally, semblance volumes were created
from all data sets to support the interpretation of faults and stratigraphic pinch-outs.
A number of projects were instigated on the Goldeneye data (test reprocessing 1997-streamer data,
OBC-reprocessing, Rock Properties Analysis, AVO-modelling, etc.) in order to better understand the
factors determining the poor seismic data quality over the field, but the primary factor is the lack of
acoustic impedance contrast at Top Captain Sandstone.
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PETERHEAD CCS PROJECT Seismic Processing
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4
4.3. 2001 3D Pre-Stack Depth Migration (PreSDM)
The dedicated 1997 3D East Ettrick seismic survey was adequate to delineate the field and to proceed
with field development planning. However, in order to reduce risks (associated with structural
uncertainty, the degree of reservoir compartmentalisation and uncertainty associated with the
stratigraphic pinch-out in the north of the field) and to optimise well positioning, the Goldeneye
PreSDM project was undertaken with the aim to deliver a substantial improvement in the seismic
image at reservoir level.
The data were reprocessed from field tapes in 2001. Other important processing steps were:
Resample 2 ms to 4 ms.
Tau-P deconvolution to attenuate water-bottom multiples.
Data depopulation to 48 fold in an 18.75 m x 18.75 m bin.
Radon demultiple to attenuate long period multiples.
The PreSDM project plan was based on re-processing of input seismic data, construction of an initial
velocity model and two stacklamp (image gather) runs to update the model. The main steps were:
Build initial velocity model, without coal bodies.
Use the initial model to migrate the high density input seismic data set (with reduced
maximum offset and reduced maximum TWT) on a coarse grid; update the shallow section of
the model; incorporate coal bodies in the model as a gridded layer.
Use the updated, hybrid model to migrate a depopulated data set (dropping alternate shots)
on a coarser grid and update the deeper part of the model.
Optimise migration parameters using 3D-in-2D-out tests.
Migrate four key lines (3D-in-2D-out) to assess value of PreSDM (volume migration tollgate).
Volume migration and post-migration processing.
Post-migration processing involved residual moveout (RMO) correction, attenuation of multiples,
residual gain application, random noise attenuation, K filtering in cross-line direction, mild amplitude
deabsorption, bandpass filtering, and the generation of angle stacks (angle of incidence ranges 0-11°,
12-22°, and 23-33°).
The inclusion of the shallow coal bodies as a gridded layer (see Figure 4-1) reduced the overburden
imprints at reservoir level but probably influenced imaging to a lesser extent.
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5
Figure 4-1: Gridded coal bodies in the final velocity model (coordinates in m; velocity in m/s)
The PreSDM volume showed a marked improvement in continuity, resolution and fault definition.
Figure 4-2 shows a comparison of PosSTM (1999) and PreSDM (2001) data. On the latter dataset
the Plenus Marl and Top Captain (2100 ms) are more easily mapped and fault definition on the Top
Zechstein is improved.
Figure 4-2: Comparison of PosSTM (1999) and PreSDM (2001) volumes
2001 PreSDM Volume1999 PosSTM Volume
Top Chalk
Top Zechstein
Top Triassic
Base Cretaceous
Plenus Marl
(Trace 12740)
4 km approx.
2000 ms
2500 ms
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6
4.4. 2010 HiDef processing
The East Ettrick survey was subjected to High Definition Processing in 2010 to allow better images
of shallow seismic features and overburden artefacts. The reprocessed area covers that of the
PreSDM dataset, about 140 km2, and focuses on the first 1,000 m below mudline. The approach
makes use of the near offset data only and outputs the data on a fine output bin grid, which is
typically 6.25 m by 6.25 m. The workflow required a high quality pre-processing sequence, especially
in terms of noise and multiple attenuation. Therefore a number of (near) offsets were used in the
final (PreSTM) stack in order to reduce remnant multiples and improve the general signal to noise
ratio. A comparison between PreSDM and HiDef results at the level of the Eocene Beauly
Formation is shown in
Figure 4-3: Comparison of 2001 PreSDM and 2010 HiDef data
. It should be noted that the sharper imaging at this level and a number of palaeo-seafloor piercement
structures not resolvable on the PreSDM. The resultant volume post-dated the main horizon
interpretation and was used to address shallow overburden questions only.
Figure 4-3: Comparison of 2001 PreSDM and 2010 HiDef data
5. Seismic-to-Well Ties
Seismic-to-well ties were generated to create a synthetic seismic trace from the P-impedance log and a
zero-phase wavelet. This was primarily focused at reservoir level to ensure accurate picking of the
internal reservoir units. All synthetics were bulk shifted so that the integrated time matched the
synthetic response at the Top Plenus Marl horizon – the nearest consistent tie point above the Top
Captain. At shallower levels, the Top Horda was another important tie point, a strong peak (soft
kick) marking a decrease in acoustic impedance.
Figure 5-1 shows the synthetic for the type well (well 14/29a-3) for this interpretation. The top of the
Captain Sandstone reservoir in this well corresponds to a zero crossing at 2034 ms. Figure 5-2 shows
the well tie for the 14/29A-2 well which lies just north of the field where the Captain Sandstone has
pinched out and the Rødby Formation lies directly on the pre-Captain Scapa Formation.
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7
Figure 5-1: Seismic-to-well tie through reservoir section (14/29a-3), depths in ft [1ft = 0.3048m].
There is no Captain sandstone present in well 14/29a-2, and tying to the Top Rødby there is a clear
soft kick correlation with the Base Cretaceous, as there is in all the Goldeneye wells (Figure 5-2).
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8
Figure 5-2: Seismic-to-well tie for well 14/29a-2
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PETERHEAD CCS PROJECT Horizon Interpretation
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9
6. Horizon Interpretation
A detailed seismic interpretation was carried using reflectivity, semblance and Elastic Acoustic
Impedance (AI) volumes to provide input horizons to the Goldeneye Field Static Model and to the
Overburden Static Model, and to the Aquifer Static Model.
In total twenty horizons from the seabed down to the Top Zechstein were interpreted across the 3D
PreSDM seismic cube (see Table 6-1 and Figure 6-1). The shallower more continuous events were
easily autotracked, whilst the deeper events were picked on a seed grid and then autotracked where
possible.
Table 6-1: Interpreted seismic horizons
Horizon Display Response Pick Quality
Top Nordland Gp Red Trough Good
Top Lark Fm Red Trough Fair - Good
Top Horda Fm Black Peak Very Good
Top Beauly Fm Red Trough Fair – Good
Top Coals Black Peak Good
Top Dornoch Mudst Red Trough Good
Top L Balmoral Sst Red Trough Poor – Fair
Top Chalk Gp Red Trough Good
Top Tor Fm Red Trough Fair – Good
Top Hod Fm Black Peak Fair – Good
Top Plenus Marl Black Peak Good
Top Rodby Fm Black Peak Fair
Top Captain Reservoir ± Zero Crossing Poor – Fair
Top Captain C Unit Black Peak Poor
Top Captain A Unit Black Peak Poor
Base Captian Reservoir Variable Poor
Top Scapa Set Red Trough Poor – Fair
Base Cretaceous
Unconformity
Black Peak Fair – Good
Top Triassic Gp Red Trough Fair
Top Zechstein Gp Red Trough Poor - Fair
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Figure 6-1: Seismic section (S-N) in depth through wells 20/4b-6 and 14/29a-2 showing
interpreted horizons.
Note: Well 14/29a-3 has been projected onto the section.
20/4B-6
14/29A-3
14/29A-2
T Nordland Gp
T Westray Gp
T Stronsay Gp
T Moray Gp
T Dornoch Mudst Unit
T Lista Fm
T L Balmoral Sst and Tuffite Unit
T Chalk Gp
T Tor Fm
T Hod Fm
T Plenus Marl Fm
T Rodby Fm
T Scapa Sst subunit
T Kimmeridge Clay Fm
T Heather Fm
T Zechstein Gp
T Rotliegend Gp
TD
T Nordland Gp
T Westray Gp
T Stronsay Gp
T Moray Gp
T Dornoch Mudst Unit
T Lista Fm
T L Balmoral Sst and Tuffite Unit
T Chalk Gp
T Hod Fm
T Plenus Marl Fm
T Rodby Fm
T Captain Sst subunit
T Captain Sst Subunit C
T Captain Sst Subunit A
B Captain Sst subunit
T Heather Fm
T Nordland Gp
T Westray Gp
T Stronsay Gp
T Moray Gp
T Dornoch Mudst Unit
T Lista Fm
T L Balmoral Sst and Tuffite Unit
T Chalk Gp
T Tor Fm
T Hod Fm
T Plenus Marl Fm
T Rodby Fm
T Captain Sst subunit
T Captain Sst Subunit C
T Scapa Sst subunit
T Kimmeridge Clay Fm
T Heather Fm
T Fladen Gp
2400 3200 4000 4800 5600 6400 7200 8000 8800 9600 10400
2400 3200 4000 4800 5600 6400 7200 8000 8800 9600 10400
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Seismic
Cross-Section
Z-Scale (ft)
Owner(s)
Horizontal Scale (m)
Date
North-South Seismic Section (Depth in f t)
1:1
Goldeney e Project Team
1:35000
September 2010
Shell UK Ltd
S N
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PETERHEAD CCS PROJECT Horizon Interpretation
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11
6.1. Top Nordland Group
This is a good quality hard kick, marking the seabed. Water depths are fairly constant around 400 ft
[122 m] deep.
6.2. Top Lark Formation (Top Westray Group)
The Lark pick is good quality across much of the AOI (Area of Interest).
6.3. Top Horda Formation (Top Stronsay Group)
The Top Horda Formation is marked by a strong amplitude reflection that can be very easily
autotracked across the survey. It marks a sharp downhole decrease in GR from the glauconite-rich
shales of the Lark Formation.
6.4. Top Beauly Member (Top Moray Group/Dornoch Formation)
The top Beauly reflector is a weak negative preceding the underlying high amplitude coals. The
horizon consists of a varying overburden of Early Eocene fan deposits, which wedge generally
eastward. A “Supra-Beauly wedge” of anomalously high (7400 ft/s [2255 m/s]), constant velocity
sediment was identified between the 14/28b-2 and 14/29a-3 wells (Figure 8-1) which is an important
layer in the depth conversion. The Beauly Formation comprises a complex association of sands, silts,
mudstones and lignites and represents fresh to brackish water sedimentation in a paralic, coastal plain
environment.
6.5. Top Coals
The top of this lignitic coal package is marked by very bright high amplitude reflectors. The coaly
beds show lateral variability in thickness (decreasing from east to west). The maximum thickness of
the coal interval above the field is approximately 200 m [660 ft] thick. The paleo-shoreline is very
clearly observed in semblance time slices and shows the shoreline regressing/retreating westwards,
marked by the outlets of subaerial channels and estuaries (see Figure 6-2). These paleo-shorelines
create sharp north-south lineaments over the Goldeneye Field that cause significant seismic artefacts
in underlying layers (Figure 9-5).
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PETERHEAD CCS PROJECT Horizon Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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12
Figure 6-2: Paleo-shoreline and drainage network as observed in the semblance map (from the
Greater Ettrick 3D survey) through the Eocene coals. Semblance extracted from
interpreted coal event at approximately 760-975 m TVDSS.
Note: Field outline (OWC at 2619 m) is superimposed on this image.
6.6. Top Dornoch Mudstone Unit
The internal subdivisions of the Dornoch Formation exhibits variable log signatures and a
discontinuous seismic response. As a result, in the Goldeneye area the Top Dornoch Mudstone unit
is approximately equal to the base of a lignitic coal package which is seismically interpretable. This is
a good quality negative trough below the bright amplitude coal packages. This coaly package
generates considerable multiples and causes a lack of contrast (acoustic transparency) in the thick
sequence of Montrose Group shales and sands (Lista Formation) below.
6.7. Top Lower Balmoral Sandstone and Tuffite Unit
This horizon in the lower part of the Mey Sandstone Member exhibits lateral variation due to on-
lapping horizons of differing lithology. Further calibration of this horizon for the eastern half of the
survey area is required from wells and seismic data to the east from well 20/5b-3. It is a difficult
event to consistently track across the survey area.
6.8. Top Chalk Group/Top Ekofisk Formation
The horizon is lithologically quite variable due to erosion cutting down through the upper, and
slower velocity, stratigraphic units. The Ekofisk thins to the south west, and merges into the Top
Tor seismic loop. The top of the Chalk is an important velocity boundary that marks the top of
deeper high velocity units (relative to the overlying Tertiary section).
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PETERHEAD CCS PROJECT Horizon Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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13
6.9. Top Tor Formation
This is a dominant negative reflector that is relatively straight forward to map. Mapping difficulties
are only encountered where the Ekofisk is thin or strongly eroded. It has an extremely high relative
velocity, circa 16,000 ft/s log velocity.
6.10. Top Hod Formation
Top Hod is mapped as a positive reflector due to a reduction in velocity from the Tor. The pick is a
low frequency positive event that suffers from doublet interference, resulting in a disturbed
autotracked horizon. The interval velocity in this unit is nearly a constant 14,000 ft/s.
6.11. Top Plenus Marl Formation
The Plenus Marl is an excellent positive reflector and is regionally identifiable. It is a dominant
acoustic impedance contrast which provides a reliable marker to align synthetic with the seismic
when doing seismic to well ties.
6.12. Top Rødby/Base Hidra Formation
The Top Rødby horizon is recognised regionally in the Outer Moray Firth area and is a low-
frequency positive event. The long wavelet period of this event, up to 30 ms, causes timing problems
with the horizon interpretation when autotracking, producing a noisy surface. This medium to high
confidence seismic pick appears one cycle beneath the Plenus Marl horizon and has a good seismic-
to-well tie. The horizon assists in constraining the Top Captain interpretation as there is at least one
black loop present between the Top Rødby and Top Captain reservoir at all well control points
within the field.
6.13. Top Captain Sandstone (Subunit E, Top Reservoir)
The turbiditic Captain Sandstone reservoir exhibits a variable seismic character over the Goldeneye
Field and its interpretation is hindered by the lack of P-wave impedance contrast with the overlying
Rødby shales. Seismic-to-well ties demonstrate that the Top Captain seismic reflector changes
polarity from a plus/minus zero crossing to a positive black loop and to a negative red loop in
different parts of the survey. In order to reduce uncertainty of exactly where this reflector changes
character, the Top Captain seismic pick has been consistently interpreted as a plus/minus zero
crossing in this study. Any resulting seismic-to-well mis-tie will at most be one quarter of a cycle
loop out. The detectable and resolvable limits of the seismic data at reservoir level are about 9 m and
23 m respectively. In the time-depth conversion all horizons have been tied back to true well depths
by means of residual error correction surfaces. The Elastic AI volume did not assist in the definition
of top reservoir, although it did give guidance to the form and geometry of reflector packages.
Figure 6-3 shows the inconsistent top reservoir reflector in wells 20/4b-6 and 14/29a-3. Given the
lack of reflector continuity, a modelling approach to the interpretation was also necessary to decide
where to cut across reflectors in order to tie the wells. This was achieved using the AI, offset and
semblance volumes. This has resulted in a combination approach that allows the interpretation to
honour the seismic data in terms of reflection character where ever possible, and a modelling
approach that allows a consistent horizon interpretation to the well data.
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PETERHEAD CCS PROJECT Horizon Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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14
Figure 6-3: North-south seismic section in depth (ft) through wells 20/4b-6 and 14/29a-2.
Note: 14/29a-3 is projected onto cross section.
The Top Captain was interpreted in two phases. Initially a fine 4x4 seed grid was interpreted with
infill of a finer grid where necessary to constrain the interpretation over the Goldeneye Field area and
the 14/29a-4 Hoylake discovery well. This horizon was picked to determine the overall structure of
top reservoir and was used as input to the Elastic AI inversion as part of the low frequency
background model. The second stage of the interpretation made use of the AI volume (together with
the reflectivity volume) to produce a high, mid and low case interpretation.
Top Captain Base Case: This horizon is picked on a plus/minus zero crossing and
represents the base case interpretation regarding the spatial extent (44 km2) of the Top
Captain reservoir. This case allows the Top Captain to drape over the northern bounding
fault to a maximum of approximately 100 m north of the fault. This drape is consistent with
the depositional model as it is interpreted that the mini-basin and northern bounding fault
were present prior to the Captain Fairway deposition with the fault marking the northern
edge of the channel. The horizon pinches out to the south, but extends to the west and east
of the field (see Figure 6-4). This base case interpretation was used in the Goldeneye Full
Field static reservoir modelling.
Top Captain High Case: This high case represents the most optimistic interpretation. If
there is the ability to take the pick higher in time in areas of poor seismic quality this horizon
honours it yet remains consistent with the principle of a positive black loop always being
present between the Base Hidra and Top Captain reservoir. It is also the most spatially
extensive (46 km2) of the three mapped cases and extends the top reservoir 200 m+ north of
the bounding fault and further to the south than the base case.
Page 30
PETERHEAD CCS PROJECT Horizon Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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15
Top Captain Low Case: This horizon represents the most pessimistic interpretation. In
order to capture uncertainty regarding reflector character this has been picked on the negative
red loop immediately beneath the mid and high case plus/minus zero crossing, and covers
the least area spatially (43 km2). The horizon barely extends over the northern bounding fault
and pinches less far to the south than the base case.
Figure 6-4: Top Captain Sandstone (base case) in depth.
Note: BCU (Base Cretaceous Unconformity) Northern Bounding Fault projected onto surface as dashed black line.
Both the seismic and semblance data were interpreted to include as many faults/baffles as possible
(see Figure 7-1) for the Top Captain reservoir to provide flexibility for the 3D static modelling. This
resulted in the mapping of numerous E-W faults at top reservoir that have almost no heave or throw.
The data suggests the Captain Sandstone units have been subject to slumps and slides post deposition
rather than excessive brittle fracture. Slump planes are suggested which appear to sole out on the
Base Cretaceous Unconformity. These slump planes are shallow angle and poorly imaged on seismic,
but suggest sand-on-sand juxtaposition and are therefore not considered as potential flow barriers.
6.14. Intra Captain Subunit C
This horizon is the top of the intra-reservoir shale unit that separates the D and A Unit sandstones in
the Goldeneye Captain reservoir sequence. This important horizon marks the base of the high net-
to-gross, high porosity D sand unit that contains the majority of the GIIP (Gas Initially In Place). All
three mapped cases (high, mid, low case) have been consistently picked on a positive loop with
extensive use of the Elastic Band Pass AI inversion volume that allows increased confidence in
picking this intra-reservoir reflector. This horizon interpretation is well constrained between the four
-9000
-9000
-9000
-9000
-9000
-8400
-8400
-8400
-8400
-8400
473600 474400 475200 476000 476800 477600 478400 479200 480000 480800 481600 482400 483200 484000 484800 485600 486400 487200 488000 488800 489600
473600 474400 475200 476000 476800 477600 478400 479200 480000 480800 481600 482400 483200 484000 484800 485600 486400 487200 488000 488800 489600
6424
000
6424
800
6425
600
6426
400
6427
200
6428
000
6428
800
6429
600
6430
400
6431
200
6432
000
6432
800
6433
600
64240006424800
64256006426400
64272006428000
64288006429600
64304006431200
64320006432800
6433600
0 500 1000 1500 2000m
1:44000
-9450-9300-9150-9000-8850-8700-8550-8400-8250
DepthLegend
UKCS BlocksPreSDM Seismic ExtentGoldeneye OWC 8592 ftGoldeneye GOC 8568 ftCaptain Sandstone Extent
Abandoned, oil and condensate showsAbandoned, dryAbandoned, gas shows, condensate to surfaceAbandoned, gas showsProducing, gas and condensate to surface
Abandoned, oil shows
Surface name
Top Captain Base Case
Shell UK Ltd
Map Reference Number
Model Name/Horizon Name
Map Date
Owner(s)SP-OB020D3-5.4
Goldeney e Field
September 2010
Goldeney e Project Team
Country
Projection
Datum
Coordinate System
Central Meridian
Geodetic Parameters
Unit of Measure
UK
TM 0 NE
ED 50
ED 1950 TM 0 N
0 deg
EPSG 1311
Metres
14/28b14/28c 14/29a
14/29d
14/29e 14/30c
20/3b 20/4a
20/4b
20/4c 20/5f
-9400
-9200
-9200
-9000
-9000
-9000
-9000
-9000
-8800
-8800
-8800
-8800
-8800
-8800 -8
800
-8800
-8400
-8600
-8600
-8600
-8600
-8600
-8600
-8600
-8400
-8400
-8400
-8400
-8200
473600 474400 475200 476000 476800 477600 478400 479200 480000 480800 481600 482400 483200 484000 484800 485600 486400 487200 488000 488800 489600
473600 474400 475200 476000 476800 477600 478400 479200 480000 480800 481600 482400 483200 484000 484800 485600 486400 487200 488000 488800 489600
6424
000
6424
800
6425
600
6426
400
6427
200
6428
000
6428
800
6429
600
6430
400
6431
200
6432
000
6432
800
6433
600
64240006424800
64256006426400
64272006428000
64288006429600
64304006431200
64320006432800
6433600
0 500 1000 1500 2000m
1:44000
-9550-9500-9450-9400-9350-9300-9250-9200-9150-9100-9050-9000-8950-8900-8850-8800-8750-8700-8650-8600-8550-8500-8450-8400-8350-8300-8250-8200
DepthLegend
UKCS BlocksPreSDM Seismic ExtentGoldeneye OWC 8592 ftGoldeneye GOC 8568 ftCaptain Sandstone Extent
Abandoned, oil and condensate showsAbandoned, dryAbandoned, gas shows, condensate to surfaceAbandoned, gas showsProducing, gas and condensate to surface
Abandoned, oil shows
Surface name
Top Captain Base Case
Shell UK Ltd
Map Reference Number
Model Name/Horizon Name
Map Date
Owner(s)SP-OB020D3-5.4
Goldeney e Field
September 2010
Goldeney e Project Team
Country
Projection
Datum
Coordinate System
Central Meridian
Geodetic Parameters
Unit of Measure
UK
TM 0 NE
ED 50
ED 1950 TM 0 N
0 deg
EPSG 1311
Metres
14/28b14/28c 14/29a
14/29d
14/29e 14/30c
20/3b 20/4a
20/4b
20/4c 20/5f
14/29a-2
N.P.
GYA03
-8388 GYA04
-8348
14/29a-4
-8745
GYA02S1
-8286
GYA05
-8257
14/29a-5
-8393
20/4b-6
-8511
14/29a-3
-8265
20/4b-7
-8546
GYA01
-8265
20/4b-3
-9019
Page 31
PETERHEAD CCS PROJECT Horizon Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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16
wells in the field (14/29a-3, 14/29a-5, 20/4b-6 and 20/4b-7). The Top C spatial extent and pinch-
out uncertainty increases away from these wells so low, base and high case interpretations were
generated. The differences between these mapped cases are primarily in a north-south direction over
the survey area and they have similar extents to the east and west.
Top C Unit Base Case: Unit C pinches out to the west, as it is absent in the 20/4b-3 well,
and very thin in 14/29a-4. The base case has an approximate areal extent of 35 km2.
Top C Unit High Case: This case represents the high pick in TWT and therefore the most
pessimistic in terms of the D unit thickness. Wherever ambiguity in the seismic pick allows
this pick remains the shallowest in TWT. As a result the mapped horizon extends the
furthest to the north of the northern boundary fault and the least to the south. The high case
has an approximate areal extent of 31 km2.
Top C Unit Low Case: This is picked on the low case in TWT and therefore allows the
greatest thickness in the D reservoir unit. Generally it does not extend north of the northern
bounding fault but extends furthest south of all three cases. The low case has an approximate
areal extent of 36 km2.
The fault interpretation is consistent with the methodology described for mapping faults at top
reservoir level. Significant effort was taken to capture any intra-reservoir faults that may have caused
compartmentalisation within the Goldeneye Field.
6.15. Intra Captain Subunit A
This horizon marks the base of the intra-reservoir C Unit shales and the top of the basal A Unit
sands. This horizon is consistently picked as a positive loop. The Captain A Unit sands are only
present in wells 14/29a-3 and 14/29a-5 and mark the base of the reservoir sequence within the mini-
basin in the centre of the field. These A Unit sands are highly erosive in nature but they are not
interpreted to extend outside the area of the central mini-basin as, it is limited to the north, south and
west by faults, and is interpreted to pinch-out onto the Base Cretaceous Unconformity high to the
east, sub-cropping beneath C Unit shales or D Unit sands. The high and low case field
interpretations are shown in Figure 6-5.
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PETERHEAD CCS PROJECT Horizon Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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17
Figure 6-5: Cross sections though the Goldeneye Field showing high and low case interpretations.
Well paths projected onto lines of section. Fluid contacts extended for clarity.
6.16. Base Captain Sandstone (Base Reservoir)
The Base Captain horizon, in combination with the Top Captain horizon, has a bearing on the
position of the northern pinch-out of the Captain sands and the reservoir Gross Rock Volume
(GRV) in the north of the field where the Base Captain is interpreted to rise above the hydrocarbon
water contact. This horizon is the least well defined in this study. The base of the Captain varies in
wells from Captain A unit sands in wells 14/29a-3 and 14/29a-5, to Captain C unit shales in wells
20/4b-6 and 20/4b-7, and Captain D sands in wells 14/29a-4 and 20/4b-3. There is no Captain
reservoir in well 14/29a-2 and so the base reservoir interpretation is known to terminate south of this
well. As a result, the seismic response of the Base Captain is variable across the survey. Resolution
LegendWell Symbols
Aband., gas &
cond. to surf.
Status Unknown
Aband., gas
shows
Producing, gas &
cond. to surf.
Fluid Contacts
Coordinate Reference
SystemCountry:
Projection:
Datum:
Coordinate System:
Central Meridian:
Geodetic Parameters:
Unit of Measure:
UK
TM 0 NE
ED50
ED 1950 TM 0 N
0 deg
EPSG 1311
Metres
A
A’
B’B
100
0
250
50
200150
f
e
e
t
Horizons
Solid=Shallowest, Dashed = Deepest
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PETERHEAD CCS PROJECT Horizon Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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18
at base reservoir level is at best moderate. This has led to a combination of tracking a negative red
loop where possible outside of the mini-basin, a positive black loop that corresponds to the Base
Cretaceous Unconformity within the mini-basin, but modelling a base reservoir pick in the areas
between the two where uncertainty exists away from well control and/or the horizon is interpreted to
erode the underlying sediments. Regional interpretations show that the Captain Sands pinch-out
south of the field and do not extend to wells further south in the 20/4c block.
6.17. Top Scapa Sandstone Subunit
The distribution of the Scapa Sandstone is an indication of the erosive nature of the overlying
Captain Sandstone mass flow deposits. There is no Scapa present in wells 14/29a-3 and 14/29a-5.
Both these wells have a complete Captain reservoir section. The Scapa Sandstone is also not present
in wells 14/29a-4 and 20/4b-3. The Scapa has been mapped with a 3x3 seed grid in an attempt to
constrain the Base Captain/base reservoir interpretation.
6.18. Base Cretaceous Unconformity (BCU)
The Base Cretaceous Unconformity was interpreted on a fine 2x2 seed grid with particular emphasis
on structural style and correlated fault patterns. In addition to the reflectivity seismic data, a
semblance volume, and both time-slices and sections through this volume were extensively used in
producing a high confidence fault interpretation for this horizon. The horizon pick is a positive
black peak, representing a reduction in impedance, marking the top of the Kimmeridge Clay
Formation. This is generally a high confidence reflector, exhibiting a consistent and correlatable
seismic response with generally clear offsets and changes in dip marking fault throws. The reflector
is weak and poorly imaged in some parts of the field, probably due to erosion by the Captain Sands.
There is also onlap onto the South Halibut Shelf and interference from other fringing sediments such
as the Lower Cretaceous Scapa Sandstone.
6.19. Top Triassic (Top Heron Group)
The Top Triassic pick is a fair quality event that shows the dominant structural trends in the
Goldeneye area.
6.20. Top Zechstein Group
The Top Zechstein was briefly mapped across the AOI. It is a poor quality negative trough.
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PETERHEAD CCS PROJECT Fault Interpretation
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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19
7. Fault Interpretation
The Goldeneye faults were interpreted using the 2001 PreSDM reflectivity data together with a
semblance volume. The Goldeneye Field fault interpretation was carried out in two iterations
concurrent with the two-stage horizon interpretation approach, with emphasis on both the structural
style of (a) the Base Cretaceous Unconformity horizon and (b) the intra-reservoir faults. Firstly close
attention has been paid to the fault patterns at the Base Cretaceous Unconformity level which
describe the basement of the Goldeneye accumulation and the overall field morphology. Secondly
during the horizon interpretation that involved iteration with the Elastic AI impedance data, detailed
fault mapping identified faults/baffles at the top, intra and base reservoir reflectors that might act as
barriers or conduits to CO2 flow during injection. This approach generated as many intra-reservoir
faults as possible in order to enable sensitivity to fault density to be incorporated into the
static/dynamic models of the Goldeneye Field. Fault throws and heaves were calculated, and fault
polygons digitised to represent each correlated fault. These polygons have been QC’d (Quality
Controlled) by overlaying them on amplitude maps extracted from the semblance data along each
relevant horizon.
7.1. Top Rødby/Top Captain Faults
Fault interpretation was focused on the Top Rødby and Top Plenus Marl Formations. To assist in
interpretation, a Root Mean Squared (RMS) amplitude of the semblance seismic volume was
extracted around these two surfaces (-30 ms and +50 ms search window) and displayed as an
attribute on the surfaces. The mapped faults are of limited vertical and lateral extent with small
throws that do not offset the sealing Rødby shales, and run approximately E-W, matching the
observed regional structural trends. The faults in the top seal are usually a bit steeper than in the
Captain Sandstone. The faults are concentrated towards the east of the Goldeneye structure.
The greatest fault density within the Captain Sandstones is evident around well 14/29a-3 where
fracture zones have been identified in core from the Captain Unit D reservoir interval (see Figure
7-1). By contrast, few fracture zones have been identified in core from well 14/29a-5 which is
located in an area with fewer mapped faults. However, blocks of Kimmeridge Clay have been
identified within the lower Captain (Unit A) reservoir interval in well 14/29a-5. These blocks are
believed to have been sourced from the area to the north-east of the well beyond where the limit of
the Captain sands is defined by a mapped fault. The mapped pattern does not reflect that faults were
active throughout deposition of the post-Captain Unit A reservoir interval, i.e. Units C, D and E, but
suggests a younger, post-Captain deposition phase of faulting (Tertiary).
7.2. Intra Reservoir Faulting
There is little evidence for intra-reservoir compartmentalisation given the seismic resolution. Any
faults propagating up through the reservoir from deeper horizons appear to have little or no throw,
therefore any juxtaposition in the upper unit will be sand-on-sand and are not expected to present
any barriers to CO2 flow.
7.3. Base Captain Faults
The Base Captain fault trends also parallel regional trends. The mapped faults are continuous but do
not totally extend across the accumulation. The fault pattern suggests a strong pre- and/or
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PETERHEAD CCS PROJECT Fault Interpretation
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20
syn-depositional fault influence on the lower Captain reservoir interval. The distribution of the lower
(Captain Unit A) reservoir interval, which is present in wells 14/29a-3 and 14-29a-5 but absent in
wells 20/4b-6 and 20/4b-7, appears to be related to the observed Base Captain faults. This lower
Captain reservoir thickness is contained within an area outlined by the mapped faults. The
boundaries to this area could represent either pre-existing (fault) scarps, suggesting a pre-depositional
influence on the lower Captain reservoir interval, or faults, suggesting active fault movement during
deposition of the lower Captain, or a combination of both processes.
Figure 7-1: Top Captain fault polygons
7.4. Base Cretaceous Unconformity (BCU) Faults
The faults at this horizon are predominantly E-W, sub-parallel to the regional structural trend. They
are apparent at BCU level but do not appear to offset the top reservoir yet influence the overall
reservoir geometry. Figure 7-2 shows the BCU fault polygons in relation to the Goldeneye wells.
There are three main fault zones that have the greatest impact on the Goldeneye Field which act to
limit the distribution of the Basal A Unit Sands confirmed by the 14/29a-3 and 14/29a-5 wells and
define the mini-basin.
To the north of the field, there is a zone of E-W southerly dipping faults that mark the northern limit
of the thickest Captain sandstone accumulation. This northern bounding fault marks the transition
from the thickest reservoir accumulation to the thin drape of sediments that extends to the north of
the fault. At BCU level it has a maximum throw of approximately 120 m and generally increases in
throw from west to east across the field. In the west of the field and north of the 14/29a-3 well, this
fault tips out and another en-echelon fault takes up the throw. This second fault has a small SW-NE
transfer or relay fault linking the two that makes the northern bounding fault a continuous feature in
this area of the field. To the south of the field, there is a zone of northerly dipping E-W faults.
There are a series of fault linkages and relay zones running to the east from the southern edge of this
zone. At the western edge of the Goldeneye mini-basin, there is a terrace consisting of two N-S sub-
parallel easterly dipping faults. The throws on these faults are approximately 20 m. This zone
appears to act as a transfer zone at the western extent of both the northern and southern fault zones.
14/29a-2
14/29a-5
20/4b-620/4b-7
14/29a-3
476000 478000 480000 482000 484000
476000 478000 480000 482000 484000
6422000
6424000
6426000
6428000
6430000
6432000
6422000
6424000
6426000
6428000
6430000
6432000
0 1000 2000 3000 4000 5000m
1:78125Goldeneye
Project name
Surface name
Model name
Horizon name
Scale
Contour inc
User name
Date
Signature
Goldeney e_CCS_All_v 2011_CL.pet
1:78125
John.J.Marshall2
12/16/2013
Map
Top Captain Faults
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PETERHEAD CCS PROJECT Fault Interpretation
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21
Figure 7-2: BCU fault polygons overlain on BCU semblance horizon
7.5. Overburden Faulting
Different fault types have developed at different stratigraphic levels and are clearly controlled by the
mechanical characteristics of the different lithologies (see Figure 7-3). There are a series of faults that
are well developed in the Chalk. These faults do not extend all the way to the seabed, and are in
general decoupled from the reservoir section. All of the shallower faults appear to have developed
after deposition of the Eocene coals. The orientation of these faults is NW-SE, with one exception
of a fault that trends NE-SW. Based on observations of borehole breakouts, the present day stress
field is NE-SW, suggesting that the latter fault might be related to relatively recent stress re-
activation. All these faults are developed in the SE flank of the field.
Most of the faults developed in the reservoir section trend WNW-ESE to E-W. This suggests that
the faults that offset the Chalk and Montrose Group sediments are most likely not related to the
syn-rift to late rift faults observed in the reservoir section, and have developed in very different
phases within the evolution of the region (late thermal subsidence phase).
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PETERHEAD CCS PROJECT Fault Interpretation
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22
Figure 7-3: North-south TWT reflectivity seismic section, equivalent semblance section and Top
Captain map for location.
Note: fault decoupling due to mechanical stratigraphy.
Fig 6.3
-9400
-920
0
-9200
-9000
-9000
-9000
-9000
-9000
-8800
-8800
-8800 -8800
-8800
-880
0
-8800
-8800
-8600
-8600
-8600
-8600
-8600
-8600
-8600
-8400
-8400
-8400
-8200
472000 473000 474000 475000 476000 477000 478000 479000 480000 481000 482000 483000 484000 485000 486000 487000 488000 489000 490000
472000 473000 474000 475000 476000 477000 478000 479000 480000 481000 482000 483000 484000 485000 486000 487000 488000 489000 490000
6426000
6428000
6430000
6432000
6426000
6428000
6430000
6432000
0 500 1000 1500 2000m
1:70000
-9500-9450-9400-9350-9300-9250-9200-9150-9100-9050-9000-8950-8900-8850-8800-8750-8700-8650-8600-8550-8500-8450-8400-8350-8300-8250-8200-8150
Depth
Surface Name
Contour inc
Map Reference
Date
Owner(s)
Top Captain (Depth in f t)
50
SP-OB020D3-Enclosure 2
September 2010
Goldeney e Project Team
Shell UK Ltd
0 800 1600 2400 3200 4000 4800 5600 6400 7200 8000
0 800 1600 2400 3200 4000 4800 5600 6400 7200 8000
-11500
-11000
-10500
-10000
-9500
-9000
-8500
-8000
-7500
-7000
-6500
-6000
-5500
-5000
-4500
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
-11500
-11000
-10500
-10000
-9500
-9000
-8500
-8000
-7500
-7000
-6500
-6000
-5500
-5000
-4500
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
0 2000 4000 6000 8000
0 2000 4000 6000 8000
Distance, [m]
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
Z,
[ft]
0 2000 4000 6000 8000
0 2000 4000 6000 8000
Distance, [m]
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
Z,
[ft]
0 2000 4000 6000 8000
0 2000 4000 6000 8000
Distance, [m]
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
Z,
[ft]
0 500 1000 1500 2000 2500m
1:70000
-30000-25000-20000-15000-10000-50000500010000150002000025000
Seismic
Cross-Section
Z-Scale (ft) Horizontal Scale (m)Seismic Ref lectiv ity Data (Inline=13036)
1:2 1:70000
Shell UK Ltd
0 800 1600 2400 3200 4000 4800 5600 6400 7200 8000
0 800 1600 2400 3200 4000 4800 5600 6400 7200 8000
-11500
-11000
-10500
-10000
-9500
-9000
-8500
-8000
-7500
-7000
-6500
-6000
-5500
-5000
-4500
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
-11500
-11000
-10500
-10000
-9500
-9000
-8500
-8000
-7500
-7000
-6500
-6000
-5500
-5000
-4500
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
0 2000 4000 6000 8000
0 2000 4000 6000 8000
Distance, [m]
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
Z,
[ft]
0 2000 4000 6000 8000
0 2000 4000 6000 8000
Distance, [m]
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
Z,
[ft]
0 2000 4000 6000 8000
0 2000 4000 6000 8000
Distance, [m]
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
-10
00
0-8
00
0-6
00
0-4
00
0-2
00
0
Z,
[ft]
00.10.20.30.40.50.60.70.80.91
Variance
Cross-Section
Z-Scale (ft) Horizontal Scale (m)Seismic Semblance Data (Inline=13036)
1:2 1:70000
Shell UK Ltd
T Nordland Gp
T Chalk Gp
T Hod Fm
T Captain
T Plenus Marl
BCU
B CaptainT Scapa
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PETERHEAD CCS PROJECT Depth Conversion
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23
8. Depth Conversion
Depth conversion for the reservoir model was carried out using a 7-layer velocity model that
honoured the Exploration and Appraisal wells and the subsequent Development wells. The method
chosen was the result of progressive refinement as well data became available, as documented below.
Going into the Goldeneye development campaign, two different velocity models were carried for the
field down to top Captain Sandstone; a 10-layer model using interval velocity vs. interval transit time
regressions, and a model developed in the PreStack Depth Migration (PreSDM) of the seismic
dataset. However, after examining the residuals from the newly drilled development wells, it was
observed that the 10-layer model was on average closer to the top reservoir encountered by the wells
than was the PreSDM model. It was decided to drop the PreSDM model and to proceed with the 10-
layer model. The Development wells had also provided new information on the overburden layers
above the Chalk and these were recorrelated: the 10-layer model was still superior to the PreSDM
model but it was found that the top Captain depth was better matched if the velocity model was
simplified to 7 layers by using a single surface to top Chalk interval. This is a consequence of limited
to no logging suites being run above top Chalk in most wells rendering picks in shallower layers more
uncertain.
The interpreted seismic time horizons were depth converted using the 7-layer depth conversion
(Table 8-1). The shallowest layer (Mean Sea Level-Top Chalk) uses a constant velocity (linear
depth/time relationship). Other intervals are calculated from well-based interval velocity vs. interval
transit time regressions. A “Supra-Beauly wedge” of anomalously high constant velocity sediment
(7400 ft/s [2256 m/s], derived from exploration well 14/28b-2 7.5 km west of the field) was inserted
above the Top Beauly Member between the 14/28b-2 and 14/29a-3 wells (Figure 8-1, Figure 8-2), in
order to capture the complex overburden velocity effects, and to achieve closure of the Goldeneye
structure to the west. A further local adjustment was made within the Top Rødby-Top Captain layer
in the area around well GYA03, to take account of a velocity anomaly (pull-up) observed in the
seismic at this well location.
Below the top Captain additional layers were required to depth convert the base Captain, Base
Cretaceous Unconformity (BCU) and horizons in the Jurassic. As the top Captain is not present over
the entire survey area, to achieve a depth conversion to the regionally recognised Base Cretaceous
Unconformity a regression was developed from Top Rødby to the BCU. The Captain Sandstone
itself and intervals below the BCU were given (different) constant velocities on the basis of the
logged time and depth data (Table 8-1)
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PETERHEAD CCS PROJECT Depth Conversion
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24
Table 8-1: Velocities used for depth conversion (depth in feet).
Interval Depth/TWT Regression Interval Velocity/Interval TWT
Regression
Surface-Top Chalk Z = 4.2387*TWT - 1369 -
Supra Beauly
Wedge
Constant velocity 7400 ft/s
added to Top Chalk depth
surface
-
Top Chalk Top Tor - V = 247.954*Chalk-Tor isochron + 17,863
Top Tor-Top Hod - V = 131.08*Tor-Hod isochron + 23,819
Top Hod-Top
Plenus
- V = 6.8924*Hod-Plenus isochron + 15,332
Top Plenus-Top
Rødby
- V = 277.9*Plenus-Rødby isochron +
23,534
Top Rødby-Top
Captain
- V = 93.879*Rødby-Captain isochron +
14,212
Captain Reservoir Constant velocity 11000 ft/s
Top Rødby-BCU V = 2.801*Rødby-BCU isochron + 11,024
BCU and below Constant velocity 10,500 ft/s
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PETERHEAD CCS PROJECT Depth Conversion
Doc. no. PCCS-05-PT-ZG-0580-00002, Seismic Interpretation Report. Revision: K03
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Figure 8-1: Supra-Beauly wedge in section.
Figure 8-2: Map view of Supra-Beauly wedge: isochore thicknesses (ft).
After depth conversion, the residuals that remained at the well locations (Table 8-2) were gridded
using Convergent Gridding without any influence limits and then added to the top structure map,
tying the surface explicitly to its observation point in each well.
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PETERHEAD CCS PROJECT Overburden Features
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Table 8-2: 7-Layer Depth Conversion residuals (ft)
Depth Conversion Residuals
Isochore Residuals (ft) Total Residual
Top
Chalk
Top Tor Top
Hod
Top
Plenus
Base
Hidra
Top
Capt
Well Top
Capt
RMS
-12 2 -7 51 -1 -13 14/29A-2 20 400
14 -7 10 20 2 8 14/29A-3 48 2304
-14 -27 31 -3 27 -5 14/29A-4 10 100
41 -11 -21 -22 -13 16 14/29A-5 -10 100
5 27 -10 -31 -40 24 20/4B-3 -24 576
-9 -10 11 -68 44 -9 20/4B-6 -41 1681
-39 51 -35 -36 -3 2 20/4B-7 -61 3721
-8 8 -12 -3 8 -6 GYA01 -14 196
-31 -10 74 30 3 -5 GYA02 62 3844
-33 24 -4 -9 -54 17 GYA03 -58 3364
50 -11 -20 -19 -17 0 GYA04 -17 289
37 -36 -18 90 -11 3 GYA05 65 4225
Average 42
Std Dev 43.4
The methodology is considered fit for CCS planning and subsequent activities.
9. Overburden Features
A number of features in the overburden cause imprints on underlying layers that need to be
understood to allow accurate horizon and fault interpretation. They are addressed in the following
sub-sections.
9.1. Seafloor pockmarks
The Top Nordland (seafloor) reflector reveals a number of circular features known as pockmarks, up
to several hundred metres wide, several metres deep (Figure 9-1). These are a common occurrence in
the North Sea and are thought to result from the periodic expulsion of gas that has become trapped
in sediments immediately below the seabed. This gas is thought to derive from a regional, low
concentration blanket which exists at slightly deeper levels below seabed and is ultimately of
thermogenic and or biogenic origin. The pockmarks do not further impinge on seismic imaging or
interpretation of deeper levels.
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PETERHEAD CCS PROJECT Overburden Features
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Figure 9-1: Pockmarks interpreted from site survey data compared to indications of seabed
depressions from interpretation of 2002 PreSDM seismic survey.
9.2. Subglacial channels
A 240 m deep 2 km wide subglacial channel runs NW-SE across the north-eastern part of the
Goldeneye Field area (Figure 9-2), cutting through the Nordland Group almost as deep as Top Lark.
The channel is of Pleistocene age and has a complex fill which has contributed to imaging artefacts
below the channel area, both imprints and lensing effects.
Figure 9-2: Subglacial channel (Field outline in red).
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28
The channel imprint effect can be seen at Top Horda where changes in horizon dip still occur
(Figure 9-3). This occurs to a greater or lesser extent on both HiDef and PreSDM throughout the
Tertiary and below.
Figure 9-3: Imprint of Pleistocene channel on Top Horda dip map
Lensing effects are considered in Section 9.5.
9.3. Palaeo-seafloor piercements
In the Eocene at the level of the Beauly Formation the 2010 HiDef processing has revealed a number
of high-impedance cones on top of one or more forced folds (Figure 9-4). These do not extend
upwards beyond the Eocene. Analogous features can be seen on shallow seismic from other areas
and they are interpreted as palaeo-seafloor piercements where gas was vented through ductile
sediments causing forced folds. A rapid westwards build-out of sediment took place across the area
in the Eocene and is the most likely cause of gas build up and escape at the time.
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PETERHEAD CCS PROJECT Overburden Features
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Figure 9-4: HiDef seismic at Beauly level through palaeo-pockmarks (purple boxes).
Note: The area in the blue box shows the combined effect of Pleistocene channel edge noise and a palaeo-seafloor
piercement. Note also the undulations at Horda level.
9.4. Eocene Coals and Palaeo-shoreline
The coals are marked by very bright high-amplitude reflectors and are illustrated in Figure 3-3 and
Figure 6-2. The coals die out eastwards at linear palaeo-shorelines and create artefacts in the
underlying layers (Figure 9-5). These are addressed in the processing & seismic interpretation sections
of this report.
• Upward Forced folds
• High impedance ‘Cone’
• Low impedance ‘plume’• Increased levels of
stacking/migration noise
• Undulation (underneath
channel)
High definition processing
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30
Figure 9-5: Edge of coal layers create vertical seismic disturbance directly below.
Note: Strong amplitude dimming is evident where a coal edge is also aligned beneath a buried glacial channel.
9.5. Lensing effects
In preparation for the Goldeneye CCS project the data acquired and processed in 2001 was scanned
for possible conduits from reservoir to surface. A single feature was identified but as the 2001 data
quality was limited it was unclear if this feature was an artefact of seismic acquisition/processing or
an image of a fluid escape feature. The feature is picked out by a seismic dim zone flanked by a bright
zone and was identified near the SE margin of the reservoir. It extends vertically through most of the
overburden and underlies the Pleistocene channel.
The seismic data was reprocessed using Shell’s proprietary HiDef technique which improved the
imaging of the shallow subsurface. On the HiDef data, it could be demonstrated that seismic events
were broken or continuous across the feature depending on offset, whereas with a genuine escape
pipe the image should be independent of offset (Figure 9-6). The imaging is consistent with a seismic
disturbed zone caused by curvature of a refracting surface at or just below the Pleistocene channel
base and is clearly not a physical escape structure.
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31
Figure 9-6: Focusing anomaly on HiDef survey
Similar features are well known from other areas of the North Sea and are in the published literature
[4] (Figure 9-7).
Figure 9-7: Vertical seismic artefacts below tunnel valleys, Danish North Sea
At longer offsets the
shallow anomaly is
undershot and
deeper horizons
seem to heal
HiDef offset 240m HiDef offset 1040m
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PETERHEAD CCS PROJECT Regional Aquifer Seismic Interpretation
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10. Regional Aquifer Seismic Interpretation
The mapping of the Lower Cretaceous Captain Sandstone Fairway over part of the Halibut Trough
was carried out across four different seismic projects. The regional seed grid density varied between
250 m to 800 m, depending on the seismic project and the mapping complexity, with an average of
some 350 m (see Figure 10-1). In addition to the Top and Base Captain reservoir, the envelope of
the Cromer Knoll Formation (Lower Cretaceous) section was also defined by mapping the Base
Hidra/Top Rødby and Base Cretaceous Unconformity (BCU) seismic markers. Seismic
interpretation of the reflectivity data was carried out on the zero-phased data sets displayed with
normal polarity (i.e. an acoustic impedance increase results in a hard kick shown as a red loop and
negative number on tape). The seismic character of the mapped horizons is summarised below:
Base Hidra/Top Rødby: Medium frequent soft (black) loop, low to high amplitude.
Top Captain Formation: Weak hard (red) loop, frequently discontinuous.
Base Captain Formation: Weak to medium hard (red) loop, frequently discontinuous.
Base Aptian Shale: Medium frequent, medium to high amplitude soft (black) loop.
BCU: Medium soft (black) loop, showing good continuity.
Figure 10-1: Top Captain TWT seismic interpretation seed grid.
After calibration with all the available well penetrations in the Captain Sandstone Fairway over the
area of interest, the Top and Base Captain events were tentatively mapped to delineate the reservoir
fairway. As mention before, the Captain Sandstone cannot unambiguously be mapped along the
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33
W E
Goldeneye
Grampian
Arch
Glenn Ridge
AtlanticCromarty Hannay
fairway due to its weak expression on the seismic data as a result of the poor impedance contrast at
top reservoir between the Captain Sandstones and the overlying Rødby shales. As a result, mapping
of coeval shales using some of the basinal wells was carried out to constrain the position and extent
of the Captain Sandstone Fairway. This was done by mapping the basinal (i.e. shaley) equivalent to
the Top Captain reservoir and the Base Aptian shale marker which slightly predates the deposition of
the Captain Sandstone reservoirs and is often eroded in the area of sand deposition. The individual
seismic interpretations were joined together in the static model with some minor editing where two
different survey interpretations overlapped.
Whilst the position of the northward pinchout of the Captain reservoir could be recognised with
some confidence, the delineation of the southward shale-out/pinchout appears less reliable, especially
in Blocks 13/29 and 20/3b. Within the mapped area, there is no clear evidence observed for large
scale faulting (clearly offset reflections) along the Captain Fairway, except in a few areas. There is
significant faulting in Blocks 21/1 and 21/2 towards the Glenn Ridge which is interpreted as the
easternmost extent of the Captain Fairway (see Figure 10-2). There is also substantial thinning of the
Captain interval observed over the Grampian Arch (Blocks 14/26a and 14/27b) to the east of the
Atlantic field. It is not clear whether the faulting around the Grampian Arch disconnects the Captain
Fairway at this location.
Figure 10-2: Regional west-east seismic section in TWT from the Cromarty Field to the Hannay
Field with the Top Captain interpretation (light blue) and the Base Captain
interpretation (green).
The Captain Sandstone turbidites were deposited in a deep marine environment, settling around the
intra-basinal highs. Two contrasting depositional models exist for the Captain Sandstones along the
Halibut Trough. The principle depositional model envisages axial flow of turbidite sands along the
Captain Fairway from west to east. The collapse of the southern flank of the Halibut shelf led to the
development of a west-east lineament parallel to the southern margins of the Halibut Horst (Jeremiah
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34
2000). Sands accumulated up on the East Orkney High could then flow along the southern flanks of
the Halibut Horst into the Cromarty Sub-basin and into the Renee Sub-basin. The alternative model
is of sand-prone turbidite fan systems feeding directly off the Halibut Horst from the north.
However, it is likely that a combination of both deposition models were active rather than one system
or the other. Around the Blake Field, the axial system probably predominates whilst around the
Goldeneye Field, and the eastern parts of the fairway, input from northerly sourced sediments are
more prominent [5].
Figure 10-3: Captain Sandstone aquifer model, isochore (ft).
The existing basin topography controlled the sand distribution of the Captain Fairway. The isochore
map (Figure 10-3) shows that the thickest deposition of Captain Sandstones occurs in the Goldeneye
Field (250 m thick in well 13/29a-3). Typically however, the Captain Fairway is 60-120 m thick.
There is a noticeable thinning over the Grampian Arch (a long-lived low relief feature in Blocks
14/26a and 14/27b), to the east of the Atlantic Field. This is the most likely major structural break
point preventing communication from the Blake Field through to the Hannay Field. The nature of
this disconnect point is perceived to be mainly sedimentological through thinning and resultant N/G
deterioration. Dynamic pressure data from the fields however, indicates that some communication
could be taking place. The eastern extent of the Captain Fairway is interpreted to be at the Glenn
Ridge (Blocks 21/2 and 21/3) where significant faulting appears to offset the Captain Sandstones.
Pressure data seems to also support this disconnection here. The western extent of the Captain
Fairway is probably limited by the Captain Ridge, a major east-west Mesozoic tilted fault block that
forms a west-plunging extension of the Halibut Horst [6] to the northwest of the Blake Field,
disconnecting the Captain Field.
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PETERHEAD CCS PROJECT Regional Aquifer Depth Conversion
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11. Regional Aquifer Depth Conversion
Depth conversion in the Halibut Trough is generally complex due to the variable Tertiary lithology
and the rugosity of the Top Chalk surface (which marks an important velocity break). Many of the
fields along the Captain Fairway have required localised edits to the velocity field in order to achieve
closure on the western flanks, counter to the regional dip from west to east. With a significantly
expanded wellstock and variable geology the field-specific 7-layer depth conversion used for
Goldeneye itself was not applicable across the entire Captain Fairway and an alternative approach was
needed.
Regional Top and Base Captain TWT seed grids were appended from several seismic workstation
projects, and depth converted in order to construct a simple static model. Three different depth
conversion techniques were attempted, and the residual mis-ties were examined:
VoK technique.
Average Pseudo-velocity from surface to Top Captain.
Two layer model Surface-Top Chalk Vav=6,913 ft/s [2,107 m/s] then Top Chalk-Top
Captain Vav=13,257 ft/s.
The two layer model (Surface-Top Chalk Vav=6913 ft/s then Top Chalk-Top Captain Vav=13,257
ft/s) actually produced the lowest RMS residuals, but the resulting Top Captain depth map suffered
from strong imprinting of the erosive features evident in the Top Chalk depth map (see Figure 11-1).
Figure 11-1: Regional Top Chalk depth surface. (Vertical exaggeration x 5).
Note: Field outlines (red) and Captain Aquifer outline (dark blue) have been superimposed onto this surface. The
structural high is the southern flank of the Halibut Horst.
70 km
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The regional aquifer 3D static reservoir model is designed to complement the detailed 3D Full Field
Static Model (FFSM) and the overburden 3D static model which are being constructed in parallel.
The FFSM is designed to model detailed geological features in the Goldeneye Field, and allow
dynamic simulation to predict fluid interactions and movements during the injection and post
injection periods. The intention is to transfer the results of the detailed dynamic simulation to the
other, less detailed models as required, so for example denser formation brine with CO2 moving by
gravity ‘out’ of the FFSM is modelled regionally in the aquifer model. This means that the three
subsurface models must share sufficient common features (such as field volume, reservoir fairway
dimensions, etc.) for this to be consistent.
As a result, the Top and Base Captain TWT surfaces were depth converted using an average velocity
map. The average pseudo-velocity (from surface to Top Captain) at each well was extracted and the
resulting velocity data points were gridded to create an average velocity map across the Halibut
Trough AOI (Figure 11-2). This simplified approach was considered fit for purpose as a regional
depth conversion.
Figure 11-2: Average velocity map (seabed to Top Captain).
Using the regional depth conversion resulted in a slightly altered Top and Base Captain surface over
the Goldeneye Field. However, in order for the detailed FFSM to be merged into the regional
aquifer model at a future date in the dynamic domain, the exact same structural envelope of the
Goldeneye Field was required in both models. As a result, the average velocity over the Goldeneye
Field was back-calculated from the Full Field Static Model time and depth surfaces. This velocity
grid was spliced into the regional average velocity grid (with smoothing at the interface) and used for
depth conversion of the regional TWT seismic interpretations. The result is an identical structure (to
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PETERHEAD CCS PROJECT Conclusions
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37
the FFSM) over the Goldeneye Field, and an average velocity depth converted Top Captain
elsewhere (Figure 11-3).
Figure 11-3: Regional Top Captain depth surface (ft).
12. Conclusions
The extensive seismic surveys over the Goldeneye field and the Captain Aquifer have been
interpreted and depth converted and the resulting seismic horizons and faults have been used as
input data to create three static model suites covering the Goldeneye Field itself, the overburden
above the Goldeneye Field, and the regional aquifer of the Captain Sandstone. These suites are
described in the document KKD 11.108 “Peterhead CCS Project Static Model Reports” and allow
characterisation of the full Goldeneye Storage Complex: the Captain Reservoir; the seal, secondary
storage and secondary seal intervals; and the associated aquifer system. These are required to assess
the storage and containment capacity of the complex.
The seismic interpretations provide evidence that there are no features indicating leakage from the
reservoir and no features that could be considered likely to impair the ability to store CO2 in
Goldeneye.
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PETERHEAD CCS PROJECT Glossary of Terms
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13. Glossary of Terms
Term Definition
AGC Automatic Gain Control
AI Acoustic Impedance
AOI Area of Interest
AVO Amplitude versus Offset
BCU Base Cretaceous Unconformity
CCS Carbon Capture and Storage
CO2 Carbon Dioxide
E East
E&A Exploration and Appraisal
FFSM Full Field Static Model
GIIP Gas Initially In Place
GR Gamma Ray (wireline log)
HiDef High Definition
Hz Hertz (SI measure of frequency)
ms Millisecond
N North
N/G Net to Gross
NMO Normal Moveout
OWC Oil water contact
PosSTM Post Stack Time Migration
PreSDM Pre Stack Depth Migration
QC’d Quality Controlled
RMO Residual Move-out
RMS Root Mean Square
S South
SCAC Surface-Consistent Amplitude Correction
SEGD Standard format for seismic data
SOF Structure-oriented Filtering
SRM Static Reservoir Model
Std Dev Standard Deviation
T Time
TVDSS True Vertical Depth Subsea
TWT Two-Way Time
UKCS United Kingdom Continental Shelf
W West
Note: The polarity convention for the seismic data is that a hard kick increase in acoustic impedance
is displayed as a negative number, shown as a red loop in all displays and figures in this report.
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PETERHEAD CCS PROJECT Glossary of Unit Conversions
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14. Glossary of Unit Conversions
Table 14-1: Unit Conversion Table
Function Unit - Imperial to Metric conversion Factor
Length 1 Foot = 0.3048 metres
Table 14-2: Well name abbreviations
Full well name Abbreviated well name
DTI 14/29a-A3 GYA01
DTI 14/29a-A4Z GYA02S1
DTI 14/29a-A4 GYA02
DTI 14/29a-A5 GYA03
DTI 14/29a-A1 GYA04
DTI 14/29a-A2 GYA05
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PETERHEAD CCS PROJECT References
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15. References
1. Upper Jurassic. In The Millennium Atlas: petroleum geology of the central and northern North Sea. 2002. 11: 157-189. Fraser, S.I., Robinson, A.M., Johnson, H.D., Underhill, J.R., Kadolsky, D.G.A, Connell, R., Johannessen, P. and Ravnas, R.. The Geological Society of London, London.
2. Timing, nature and sedimentary result of Jurassic tectonism in the Outer Moray Firth. In Tectonic Events Responsible for Britain’s Oil and Gas Reserves. 1990. 55: 259–279. Boldy, S.A.R., & Brealey, S.. Geological Society, London, Special Publications.
3. Lower Cretaceous turbidites of the Moray Firth: sequence stratigraphical framework and reservoir distribution. 2000. 6: 309-328. Jeremiah, J.M.. Petroleum Geoscience.
4. Multistage erosion and infill of buried Pleistocene tunnel valleys and associated seismic velocity effects. In Glaciogenic Reservoirs and Hydrocarbon Systems. 2012. 368: 159-172. Kristensen & Huuse. Geological Society, London, Special Publications.
5. The Kopervik fairway, Moray Firth, UK. 2000. 6: 265-274. Law, A. et al.. Petroleum Geoscience.
6. Reservoir characterisation in the Captain Field: integration of horizontal and vertical well data. 1999. : 1101-1113. Rose, P.T.S.. Petroleum Geology of Northwest Europe: Proc. of the 5th Conference.